The present invention relates to an electron beam sterilizer which sterilizes vessels being conveyed by irradiation with an electron beam.
An electron beam sterilizer which sterilizes vessels being conveyed by irradiation with an electron beam is known in the art (see Japanese Laid-Open Patent Application No. 11-137645 or No. 11-1212, for example). “Electron beam sterilizer for empty plastic vessels” according to the invention disclosed in the first cited Application comprises a feeder mechanism which feeds empty plastic vessels, a turning mechanism, an electron beam irradiation mechanism, and a discharge mechanism which discharges empty plastic vessels subjected to the electron beam irradiation.
The purpose of the turning mechanism is to secure empty plastic vessels fed from the feeder mechanism by applying a vacuum suction thereto and to cause a turning motion and a revolving motion about individual axes of the empty plastic vessels while they are secured, and the turning mechanism comprises a plurality of turntables on which the empty plastic vessels are secured and a turntable drive. The electron beam irradiation mechanism sterilizes the empty plastic vessels by irradiating them with the electron beam from the inner periphery of and in synchronism with the turning mechanism. In the arrangement of the cited invention, the electron beam irradiation mechanism includes electron beam irradiators which are equal in number to the number of turntables disposed on the turning orbit of the turning mechanism.
“Sterilizer for vessels utilizing electron beam” disclosed in the second sited Application comprises an electron beam generator disposed in a vertical position within a sterilization processing chamber, and vessel conveying means extending from the inlet to the outlet of the sterilization processing chamber. There is disposed revolution imparting means which causes a vessel to revolve at a location in front of the electron beam generator.
According to the sterilizer shown in the second citation, vessels proceed through the sterilization processing chamber on vessel conveying means (air conveyor), and are subject to a revolution as they reach the revolution imparting means. Vessels which are conveyed while revolving pass an irradiation window of the electron beam generator while revolving about their axes. Vessels which are successively conveyed in this manner are sterilized by irradiation with the electron beam as they pass in front of the irradiation window while being imparted with a revolution by the revolution imparting means, and are subsequently discharged out of the sterilization processing chamber.
In the arrangement of the invention disclosed in the first cited Application, there is a need for the provision of as many electron beam irradiators as the number of the turntables on which the vessels are secured, leading to a problem that the arrangement is expensive and bulky as a whole. By contrast, in the arrangement of the invention disclosed in the second cited Application, the electron beam irradiator is provided at a single location, but the revolution is imparted to the vessels for irradiating the electron beam around the full periphery of the vessels. The arrangement that the vessels are caused to revolve in the course of the air conveyance leads to a problem that a high speed operation is inhibited.